1061 GW-deployed vs 1128 nondeployed veterans, veterans selected from among those who had participated in 1995 mail and telephone survey

CFS based on in-person interviews according to CDC CFS criteria and exclusionary diagnoses from history, interviews, examinations, laboratory testing

OR 40.6, 95% CI 10.2-161.15

Age, sex, race, cigarette-smoking, duty type, service branch, rank

Low participation rates (53% of deployed and 39% of nondeployed), but analysis of nonparticipants and participants reveals that participants, both deployed and nondeployed, are more likely to report symptoms of CFS